OGC Catalog Service for the Web OGC Catalog Service for the Web (CS/W): experience in NASA(CS/W): experience in NASA
John D. Evans, Ph.D.John D. Evans, [email protected]@nasa.gov
NASA Geosciences Interoperability Office (GIO)NASA Geosciences Interoperability Office (GIO)Earth Science Applications DivisionEarth Science Applications Division
-/- Global Science-/- Global Science & Technology, Inc.& Technology, Inc.
Goddard Space Flight Center, Greenbelt, MDGoddard Space Flight Center, Greenbelt, MD
Introduction & overviewIntroduction & overview
● OGC CS/W specification: Spring 2004OGC CS/W specification: Spring 2004– (After many iterations)(After many iterations)
● OGC ebRIM profile: Fall 2005OGC ebRIM profile: Fall 2005● NASA experimenting with CS/W since Fall 2004NASA experimenting with CS/W since Fall 2004● Two implementations in particular:Two implementations in particular:
– ECHO CS/W connectorECHO CS/W connector (Center for Spatial Information (Center for Spatial Information Science & Systems [CSISS], George Mason University)Science & Systems [CSISS], George Mason University)
– Earth Science GatewayEarth Science Gateway (NASA Geosciences (NASA Geosciences Interoperability Office [GIO] & Compusult Ltd.)Interoperability Office [GIO] & Compusult Ltd.)
● Implementation experienceImplementation experience– Insights, opportunities, and challengesInsights, opportunities, and challenges
GMU / CSISS experience with CS/WGMU / CSISS experience with CS/W
● Bird’s eye viewBird’s eye view
- From Bai, Y., et al., 2007: Towards a Geospatial Catalogue Federation Service, Photogrammetric Engineering & Remote Sensing 73 (6), pp. 699-708
GMU / CSISS experience with CS/WGMU / CSISS experience with CS/W
● Inside the Catalogue Federation ServiceInside the Catalogue Federation Service
- From Bai, Y., et al., 2007: Towards a Geospatial Catalogue Federation Service, Photogrammetric Engineering & Remote Sensing 73 (6), pp. 699-708
RegistryObject
Classification
ClassificationSchema
……
Association
ServiceBindings
RegistryEntry
Service
ExtrinsicObject
CSWExtrinsicObject
RepositoryItem
Service Info. Model (ISO 19119)
Dataset Info. Model (ISO 19115)
NASA EOS Core System (ECS)
Slot
GMU / CSISS experience with CS/WGMU / CSISS experience with CS/W
● ebRIM model extends OGC CSW for geospatial resources
● ebRIM + OGC Catalogue Service for CS/W + OGC Catalogue Service for ISO 19115/19119
GMU / CSISS: CS/W bridge to ECHOGMU / CSISS: CS/W bridge to ECHO
● http://laits.gmu.edu:8099/ECHO9CSW2/discoveryhttp://laits.gmu.edu:8099/ECHO9CSW2/discovery
● Connects to the full, operational ECHOConnects to the full, operational ECHO● Partial ECHO–ebRIM mapping. Emphasis:Partial ECHO–ebRIM mapping. Emphasis:
– CS/W core queryables (Dublin Core)CS/W core queryables (Dublin Core)– Granules (not Collections)Granules (not Collections)
● Performance issues:Performance issues:– ECHO not fully optimized for granule-level searchECHO not fully optimized for granule-level search– ECHO 8 responds to most queries from CS/W ECHO 8 responds to most queries from CS/W
connector in under 2 minutes (used to be worse)connector in under 2 minutes (used to be worse)– ECHO 9 may further improve query performanceECHO 9 may further improve query performance
● Multiplicity of schemas poses add’l challengesMultiplicity of schemas poses add’l challenges– CS/W used as a “hub” for several different catalogsCS/W used as a “hub” for several different catalogs
NASA / GIO Earth Science Gateway (ESG)NASA / GIO Earth Science Gateway (ESG)
Earth Science Gateway (ESG)Earth Science Gateway (ESG)Service ManagerService Manager
OGCWMS
Servers
ServiceManager
Service RegistryDatabase (Oracle)
WebPublishing
Client
OGCWFS
Servers
OGCWCS
Servers
ExternalApplications/Clients
OGC CSW Requests - GetCapabilities (1) - GetRecords (2)
OGC CSW Transactions (3) - Insert - Update - Delete
OGC Repository Extensions - GetRepositoryItem (4) - PutRepositoryItem (5)
Capabilities XMLDocument (1)
Transaction Status (3)
SearchResults (2)
RepositoryItem (4)
Repository Status (3)
OGCWMS
Servers
ServiceManager
Service RegistryDatabase (Oracle)
WebPublishing
Client
OGCWFS
Servers
OGCWCS
Servers
ExternalApplications/Clients
OGC CSW Requests - GetCapabilities (1) - GetRecords (2)
OGC CSW Transactions (3) - Insert - Update - Delete
OGC Repository Extensions - GetRepositoryItem (4) - PutRepositoryItem (5)
Capabilities XMLDocument (1)
Transaction Status (3)
SearchResults (2)
RepositoryItem (4)
Repository Status (3)
Earth Science Gateway (ESG)Earth Science Gateway (ESG)Service ManagerService Manager
● ESG portal uses CS/W internally for all ESG portal uses CS/W internally for all catalog accesscatalog access– SearchSearch
– PublishPublish
– HarvestHarvest
● Public interface available for other CS/W clientsPublic interface available for other CS/W clients● Simple HTML client can query other CS/W serversSimple HTML client can query other CS/W servers
ESG in OGC Web Services Testbed 3ESG in OGC Web Services Testbed 3
● Successful connections from a Refractions Successful connections from a Refractions Research CS/W client (Nov. 2005)Research CS/W client (Nov. 2005)
● Key challenge: reconciling different ebRIM Key challenge: reconciling different ebRIM representationsrepresentations– E.g., WMS Layer Extrinsic Object: is its ObjectType E.g., WMS Layer Extrinsic Object: is its ObjectType
““LayerLayer””? ? ““WMS_LayerWMS_Layer””? or ? or ““Data_SetData_Set””??– A guessing game; create equivalencies to fit queries A guessing game; create equivalencies to fit queries
coming from different clientscoming from different clients– Changing an ebRIM type name can be a headacheChanging an ebRIM type name can be a headache
● Another challenge: maintaining performanceAnother challenge: maintaining performance– Query response slowed a lot at 100k-200k records.Query response slowed a lot at 100k-200k records.– Server-side workarounds: temp tables; caching; Server-side workarounds: temp tables; caching;
returning summaries rather than full recordsreturning summaries rather than full records
ESG in OGC Web Services Testbed 4ESG in OGC Web Services Testbed 4
UAV
EO-1
Service Binding
Classification
ExtrinsicObjectobjectType =
Geometry
ExtrinsicObjectobjectType =
Context Document(WMS only)
HasFootprint
Offers
HasContext
ServiceBinding
Extents
User
OffersService
ExtrinsicObjectobjectType =
Dataset Description (Metadata Document)
HasFootprint
Describes
Classification
Classification
uuid = parent
uuid = classified_object
uuid = service
ExtrinsicObjectobjectType =
Layer / featureType /CoverageOfferingBrief
Service(WMS, WFS, WCS)
uuid = classified_object
ExtrinsicObjectobjectType =
Layer / featureType /CoverageOfferingBrief
ESG: ebRIM model of OGC Web ServiceESG: ebRIM model of OGC Web Service
ExtrinsicOjectobjectType = Legend
ExtrinsicOjectobjectType
= LayerStyle
Classification
ExtrinsicObjectobjectType = Geometry
Extents HasFootprint
Externally Links
Styles
Service(WMS, WFS, WCS)
Describes
HasLegendExtrinsicOjectobjectType =
LayerStyle
ExtrinsicOjectobjectType = Legend
ExtrinsicObjectobjectType =
Dataset Description (Metadata Document)
Offers
HasFootprint
ExtrinsicObjectobjectType = Layer, orfeatureType, orCoverageOfferingBriefExternalLink
Extents
ExternalLink
Classification
g.uuid = e.parent
uuid = classified_object
ESG: ebRIM model of OGC Web Service objectsESG: ebRIM model of OGC Web Service objects(WMS Layer, WFS FeatureType, WCS CoverageOffering)(WMS Layer, WFS FeatureType, WCS CoverageOffering)
ESG and CS/W interoperabilityESG and CS/W interoperability
● ESG as CS/W server:ESG as CS/W server:– http://esg.gsfc.nasa.gov/wes/serviceManagerCSW/cswhttp://esg.gsfc.nasa.gov/wes/serviceManagerCSW/csw – Successful CS/W connections from Successful CS/W connections from
Intergraph testbed client Intergraph testbed client – Prototype CS/W connections from European Space Prototype CS/W connections from European Space
Agency (ESA) client Agency (ESA) client [[http://eoportal.org]http://eoportal.org]● ESG as CS/W client:ESG as CS/W client:
– Successful CS/W connections to GMU/CSISS ECHO Successful CS/W connections to GMU/CSISS ECHO connectorconnector
● Differences in ebRIM representations continue to Differences in ebRIM representations continue to be the main challengebe the main challenge– Conforming to CS/W is necessary but NOT sufficient Conforming to CS/W is necessary but NOT sufficient
for catalog interoperabilityfor catalog interoperability
CS/W opportunities & challengesCS/W opportunities & challenges
● OGC CS/W interface definition is owned by OGC CS/W interface definition is owned by no-one (consensus-based)no-one (consensus-based)– Support by vendors, open source, etc.Support by vendors, open source, etc.
– Used across many different sectors of activityUsed across many different sectors of activity
● ebRIM is a promising “common ground” for ebRIM is a promising “common ground” for catalogscatalogs– Very flexible meta-modelVery flexible meta-model
– Growing momentum in e-businessGrowing momentum in e-business● Expect tools to manage the complexityExpect tools to manage the complexity
● ebRIM: not the answer BUT a good framework ebRIM: not the answer BUT a good framework for expressing the answerfor expressing the answer
CS/W opportunities & challengesCS/W opportunities & challenges
● CS/W & ebRIM complexity / generalityCS/W & ebRIM complexity / generality– Impedes wider implementationImpedes wider implementation
– Impedes wider consensus on profiles?Impedes wider consensus on profiles?
● Representing earth imagery in ebRIM:Representing earth imagery in ebRIM:– E.g., ESA’s EO products profile (slow adoption so far)E.g., ESA’s EO products profile (slow adoption so far)
● Lots of support for product orderingLots of support for product ordering● Little support for service bindingLittle support for service binding
– No one ebRIM representation will fit everyoneNo one ebRIM representation will fit everyone
– Need an imagery counterpart to Dublin Core?Need an imagery counterpart to Dublin Core?
● NASA community could enhance catalog NASA community could enhance catalog interoperability by defining one or more interoperability by defining one or more overlapping CS/W ebRIM representationsoverlapping CS/W ebRIM representations
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